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This letter reports the structural, dielectric, ferroelectric, and magnetic properties of Fe substituted nonstoichiometric STO ceramics. X-ray diffraction and Scanning electron microscope reveal the microstructure of the samples. The room temperature multiferroicity of the Fe-doped Ti-rich STO ceramics is successfully realized by M-H hysteresis loop, P-E hysteresis loop and magnetodielectric measurement. The origins of ferroelectricity may be related to the lattice distortions and antisite-like defects with net local dipoles. The ferromagnetism are mainly contributed by the competitions among the double exchange interactions, super-exchange interactions and the non-linear ferromagnetic exchange coupling. In addition, the ordered spin arrangement of the ferromagnetism is formed by the exchange interaction of Fe atom using first principle simulations.

This paper presents a systematic study on the energetic and electronic structure of the Al(111)/6H-SiC(0001) interfaces by using first-principles calculation with density functional theory (DFT). There are all three situations for no-vacuum layer of Al/SiC superlattics, and two cases of C-terminated and Si-terminated interfaces are compared and analyzed. Through the density of states analysis, the initial information of interface combination is obtained. Then the supercells are stretched vertically along the z-axis, and the fracture of the interface is obtained, and it is pointed out that C-terminated SiC and Al interfaces have a better binding property. And, the fracture positions of C-terminated and Si-terminated interfaces are different in the process of stretching. Then, the distance variation in the process of stretching, the charge density differences, and the distribution of the electrons near the interface are analyzed. Al these work makes the specific reasons for the interface fracture are obtained at last.

SrTiO3 has received increasing attention duo to the fact that small perturbation can produce outstanding physical properties. Nonstoichiometric SrTiO3 ceramics have been prepared in the range of Sr/Ti = 1.064–0.943. Their dielectric behaviors are investigated in the temperature range of 30–500 °C and in the frequency range 100 Hz to 2 MHz. It is observed that the two types of dielectric relaxation processes are caused by polar nanoregions associated with Sr non-stoichiometry and variable range hopping behavior associated with the dipolar effects for Sr/Ti>1 and Sr/Ti

In this communication, we present the results on YFe0.9Mn0.1O3 (YFM10) ceramics processed by the sol–gel route in order to study Structural, dielectric and magnetic properties. XRD shows that this compound possesses an orthorhombic structure with Pbnm space group. Temperature dependence of magnetization [zero field cooled (ZFC) and field cooled (FC) behavior] and the M (H) behavior indicate that the Fe spins order antiferromagnetically with a weak ferromagnetic moment in YFM10, which may be attributed to the complex magnetic interaction between the Mn and Fe irons. Moreover, two dielectric relaxations were distinguished by the combination of impedance and modulus analysis for the YFM10 ceramics, which could be associated with the migration of oxygen vacancies and the carrier hopping process between Fe2+ and Fe3+.

The structural, dielectric, leakage current and ferroelectric properties of the SrTi1+xO3 (x = −0.06, −0.03, 0, 0.03 and 0.06) ceramics have been investigated. X-ray diffraction and Scanning electron microscope reveal the microstructure of the samples. The Sr/Ti ratio in STO ceramics effectively adjusts their dielectric and the dc leakage behavior. In addition, the room temperature ferroelectricity of the nonstoichiometric STO ceramics is successfully realized by P-E hysteresis loop measurement. It is found that the origins of ferroelectricity for the Ti-rich and Sr-rich STO ceramics are different and may be related to the lattice distortions, the polar nanoregions and antisite-like defects with net local dipoles.

In this work, Sm 2 O 3 - and SiO 2 -codoped SnO 2 -Zn 2 SnO 4 ceramic varistors were prepared through traditional ceramic processing, and the effect of Sm 2 O 3 on the resulting microstructure and electrical properties was investigated. The results demonstrated that the ceramics were composed mainly of SnO 2 and Zn 2 SnO 4 , and Sm was distributed homogeneously in the grains and along the grain boundaries. With 0.2 mol% Sm 2 O 3 doping, the grain growth was obviously promoted. Further increases in Sm 2 O 3 to 0.4 mol% resulted in trace amount of SiO 2 and segregations containing elemental Sm via X-ray diffraction patterns and microstructure photos, respectively. In the sample doped with 0.3 mol% Sm 2 O 3 , optimal electrical characteristics of α =9.4, E B =10 V/mm, J L =46 μA/cm 2 and e ′=1.2×10 4 were obtained. Simultaneously, the sample doped with 0.3 mol% Sm 2 O 3 had the lowest conductance activation energy of 0.16 eV at temperatures lower than 110 °C. This good performance indicates that Sm 2 O 3 - and SiO 2 -codoped SnO 2 -Zn 2 SnO 4 composite ceramics are viable candidate for the manufacture of capacitor-varistor functional devices.

In this communication, we present the results on YFeO 3 and YFe 0.8 Mn 0.2 O 3 ceramics processed by the sol–gel route in order to study crystalline structure, dielectric properties. X-ray diffraction shows that this compound possesses an orthorhombic structure with Pbnm space group. Meanwhile, the dielectric properties of the samples were evaluated over broad temperature and frequency ranges. Two and three dielectric relaxations were distinguished by the combination of impedance and modulus analysis for the YFeO 3 and YFe 0.8 Mn 0.2 O 3 ceramics, which could be associated with the migration of oxygen vacancies and the carrier hopping process between Fe 2+ and Fe 3+ .

In this work, SiO 2 doped SnO 2 -Zn 2 SnO 4 ceramic composites with excellent varistor and dielectric properties were prepared through traditional ceramic processing. The obtained nonlinear coefficient α was as high as 9.6, and the breakdown electrical field EB and leakage current density JL was as low as 5.9 V/mm and 62 μA/cm 2 , respectively. At a low frequency of 40 Hz, the relative permittivity er measured at room temperature was higher than 2.5×10 4 . The nonlinear decrease of the semicircle diameter in the complex impedance spectra with increasing DC bias voltage indicates that the grain boundary effect is an important origin of the varistor and giant permittivity properties. With an increase of temperature, the relaxor peak of the imaginary part M ″ of the complex electric modulus shifted to high frequency and the activation energy E a obtained from the M ″ spectrum was about 0.31 eV, much lower than the grain boundary barrier height ϕ b . The results suggest that other mechanisms may also be responsible for the giant permittivity property besides grain boundary barriers.

Both undoped and Pr-doped STO films are fabricated on (1 1 1) Pt/Ti/SiO 2 /Si by metal organic deposition. The influence of Pr dopant on oxygen vacancies is studied using X-ray photoelectron spectroscopy and X-ray diffraction. It is found that the concentration of oxygen vacancies is not decreases with the increase of the content of higher valence Pr ions, but decreases and increases alternatively. These results are associated with the variable valence and doping position of Pr ions, and the possible causes of which are discussed.

Zn 2 SnO 4 -doped BaTiO 3 ceramics were prepared as dielectric material though a conventional solid state reaction method. The room temperature dielectric constant was improved by Zn 2 SnO 4 doping, with the appearance of diffuse phase transition and reduced dielectric loss. More importantly, the temperature stability of BaTiO 3 ceramics (Δ C / C 25°C ) was modified by varying doping contents. The temperature dependence of sample with 2% doping contents satisfied the Electronic Industries Alliance Y5V temperature characteristic specification and was near the X7R specification. The SEM micrographs indicate that the BaTiO 3 solid solution has a homogeneous fine-grained microstructure with grain size 2 SnO 4 doping contents have a tetragonal phase at RT. DPT was resulted from element substitution of Ti 4+ with Sn 4+ , as lattice parameters increasing under inter-grain stress. Results of impedance spectroscopic analysis suggest the presence of two relaxation mechanisms. One was originated from the dipolar polarization in the grain, and the other was related with the hopping charge carriers of oxygen vacancy in the grain boundary. The dielectric loss over a wide temperature range was modified by the activation energies of the two type relaxation mechanisms.

SnO2–Zn2SnO4 composite ceramics with a colossal dielectric permittivity and varistor behavior are prepared by traditional ceramic processing. By increasing bias voltage from 0 to 10 V at a low frequency (~103 Hz) and at room temperature, the relative permittivity decreased rapidly from about 20 000 to several thousand, whereas the radius of the semicircle in the complex impedance decreased and the tail gradually disappeared. However, the peak height and the position of the imaginary part of the complex modulus in the spectra were independent of the applied DC voltage. The slope deduced from the bias voltage-dependent straight lines of the double-logarithmic imaginary permittivity spectra were constant with a value of −0.63 at high frequencies and they decreased to −1 at low frequencies. The results strongly indicate that a number of weekly trapped charges existed in the ceramic bulk. From the temperature-dependent dielectric and electric modulus spectra, the trapped charge activation energy was about 0.32 eV, which may be associated with the oxygen vacancies. Based on the results, a modified equivalent circuit related to the colossal dielectric permittivity and varistor properties was proposed, in which a Warburg impedance was added in parallel with the resistance and capacitance.

The magnetic and dielectric properties of a Y2MnCoO6 ceramic have been investigated. The x-ray diffraction pattern shows that the sample has the monoclinic structure (space group P21/n). Magnetic measurements show that Y2MnCoO6 becomes ferromagnetic (FM) below TC ~75 K. More importantly, the temperature dependence of magnetization (zero field cooled and field cooled behavior) and the M(H) behavior are indicative of spin-glass-like behavior of Y2MnCoO6, which may be caused by competition between the FM and antiferromagnetic interaction. Dielectric relaxor behavior at low temperature is also observed; this arises from dipolar effects associated with the charge ordering of Co2+ and Mn4+.

Both multilayered and homogeneous BST films with the same ratio of Ba to Sr are prepared by metal-organic deposition on (111) Pt/Ti/SiO 2 /Si substrates. X-ray diffraction reveals the microstructure of the samples. Compared with the homogeneous BST film, the multilayered BST film shows improved electrical properties with smaller leakage current, larger dielectric constant, higher tunability and better ferroelectrity. These results are associated with the multilayered structure and strain-related interactions between layers, and the possible causes of which are discussed.

Densified SnO2-Zn2SnO4 composite ceramics were prepared by conventional ceramic processing and the sintering, electrical properties were investigated. The X-ray diffraction results and sintering curves showed that the pellets pressed by ZnO and SnO2 mixed powders began to shrink after Zn2SnO4 was synthesized at about 950 °C. The results suggest that the densification of SnO2-Zn2SnO4 composite ceramics cannot be attributed to the oxygen vacancies created by acceptor doping as traditional viewed. The measurement of J-E curves showed that the SnO2-Zn2SnO4 composite ceramics have good nonlinear properties (α ~ 3.9–4.5) without any other doping. Another interesting result is that the composite ceramics have low breakdown electrical field (E B ~ 10 V/mm) with high relative dielectric constant (1 kHz, e r ~ 6 × 103). Further studies demonstrate that the varistor behavior is also a grain boundary barrier effect and the barrier height is about 0.84 eV.

SnO2 ceramics with relative density about 98 % were obtained based on the addition of Zn2SnO4. The shrinkage of the ceramic samples increased sharply and got a saturated value about 13.3 % with doping more than 0.2 mol% Zn2SnO4. In the dielectric spectra, no relaxation peaks were observed and no deep trap states could be detected from 50–300 °C and 40–5 M Hz. Thus, the oxygen vacancies may not be necessary for the densification of SnO2 ceramics during sintering process. For all the samples, nonlinear electrical properties were observed and the breakdown electrical fields are in good agreement with the barrier height. With increasing Zn2SnO4 content, the activation energies E a for O− or O2− adsorbed at grain boundary decreased and the doping of Zn2SnO4 may be an important reason for the improve of grain conductivity and formation of Schottky barrier.

As a high-dielectric cubic perovskite-related material, CaCu3Ti4O12 (CCTO) has a dielectric constant of 104 at room temperature. Up to now the origin of the peculiar dielectric phenomena in CCTO is not fully understood and there are some disputes in the literature. In this paper, based a one-dimensional Ising model under static electric field, the dielectric properties of CCTO were studied. Results indicate that the theory is nearly consistent with the experiment.

Within the framework of modified Landau–Devonshire thermodynamic theory, the equilibrium polarization states and physical properties of single-domain Pb(Zr1-xTix)O3 (PZT) thin films epitaxially grown on dissimilar cubic substrates are investigated. The “misfit strain-temperature” phase diagrams are obtained for several different compositions (x = 0.75, 0.65 and 0.55) of PZT films. The presence of stability range of the monoclinic phase is the characteristic feature of these phase diagrams, which separates the stability ranges of the tetragonal phase and the orthorhombic phase. Further analysis shows that the monoclinic phase widens with the increase of Zr content, and meanwhile the center shifts from positive values of the misfit strain towards zero.

Maxwell—Wagner (M-W) theory was used to explain the dielectric relaxor behavior of BiFeO3(BFO)/Bi3.25La0.75Ti3O12(BLT) film grown on Pt/Ti/SiO2/Si substrate. The BFO film was considered to be ferroelectric film, and its temperature dependence of dielectric constant was calculated by Landau theory. BLT film was of dielectric-relaxor behavior and its temperature dependence of dielectric constant was given by Smolenski theory. The leakage currents for the BFO and BLT films were assumed to obey Poole–Frenkel emission and Schottky emission, respectively. The temperature dependent dielectric constant and loss of the BFO/BLT film were characterized, which agrees with the experiment. The enhancement of the polarization in BFO/BLT film may induced by the current leakage restraining in BFO film.

Grown-in distribution and annealing behavior of crystal-originated particles (COPs) in Czochralski silicon (Cz-Si) wafer with germanium doping have been investigated. It was found that COPs with high density but small sizes were inclined to generate in germanium-doped Cz-Si (GCz-Si) wafer. The increase of boron atoms in Cz-Si crystal with the germanium doping could benefit the formation of COPs while the oxygen interstitials in GCz-Si wafer could enhance the generation of COPs with small sizes. Meanwhile, it was suggested that the germanium doping in Cz-Si would result in the poor thermal stability of COPs. It is proposed that the combination between germanium atom and vacancy could reduce the free vacancy concentration and the onset temperature for void generation, thus forming denser but smaller void. While the stress compensation induced by boron and germanium atoms could increase the vacancy fluxes in heavy-boron doped GCz-Si crystal, the presence of oxygen atom in GCz-Si would incline to benefit the formation of inner oxide walls of void, especially with small sizes. Furthermore, thinner oxide walls within void for GCz-Si crystal are considered to be charged for the easy annihilation by the germanium doping.

The influence of stress on the spontaneous polarization in two-dimensional Bi4Ti3O12 (BiT) films is investigated by modified Landau—Devonshire thermodynamic theory. Three orientation cases of BiT unit, nine ferroelectric phases are discussed under the mechanism of strain-polarization coupling. Results show that the effect of stress on out-of-plane spontaneous polarization for all cases is small and can not clarify the origin of the effect of external stress on the net-switched charge in Nd- and La-doped Bi4Ti3O12 films. So there is a need to consider stress-induced reorientation of domains.

In the application of a set of position-thickness-dependent stress to modified Landau-Devonshire theory, the distribution of dielectric constant and the dependence of effective dielectric constant on the film thickness and the temperature have been studied in BaTiO3 films with fine grains. The results show that both the transition temperature and dielectric constant are dependent with positions. When T T > T c , a layer with giant dielectric constant appears in the film. And when T > T cfmax , the dielectric constant near the interface is higher than that near the center. The “series capacitor model” is invalid at high temperature for c-phase. The theoretical results agree with the experiment.

With the reduction in size of the features of ultra large-scale integrated (ULSI) circuits, micro-defects such as voids in Czochralski (Cz) silicon (Si) crystals play more important roles in the reliability and yield of these devices. As one of the tetravalent atoms, the behavior of germanium (Ge) doped in Cz Si crystals has attracted considerable attention in recent years. In this presentation, recent processes in the study of voids in Ge doped Cz (GCZ) Si crystals are reviewed. The grown-in characteristics of voids in GCZ wafer, including flow pattern defects (FPDs) and crystal originated particles (COPs), suggested that Ge can suppress large voids resulting in denser and smaller voids. Meanwhile, it has been found that the density of voids can be decreased by Ge doping and they can be eliminated easily in GCZ Si crystals through high temperature annealing. It is therefore speculated that the gate oxide integrity (GOI) of semiconductor devices can be improved by Ge doping. The mechanism of the effect of Ge on voids is discussed to explain the experimental results.

The behaviours of germanium doped in Czochralski (CZ) silicon have attracted considerable attention in recent years. In this article, a review concerning recent processes in the study about oxygen related defects in germanium-doped CZ (GCZ) silicon is presented. The formation of oxygen precipitates during CZ silicon growth can be improved by germanium, and the oxygen precipitation during thermal cycles can be enhanced, so that the internal gettering (IG) ability of GCZ silicon wafers for metallic impurities is improved. Meanwhile, the morphology of oxygen precipitates can be changed in GCZ silicon. Thermal donors (TDs) can be suppressed by germanium doping as the result of the reaction between germanium and point defects, while new donors (NDs) can be strongly enhanced in GCZ silicon because of a process associated with the nucleation enhancement of oxygen precipitates with germanium doping.

Landau–Devonshire theory is used to investigate the effect of external mechanical stress (or strain) on domain structure and the remanent polarization of Pb(Zr0.35Ti0.65)O3 (PZT) thin films, by considering the competition between the external stress and the intrinsic stresses. A set of intrinsic stress functions in PZT film is obtained by solving elastic mechanical equations. At room temperature, the intrinsic stresses may lead to an alternate a/c/a/c domain structure. While an external in-plane tensile stress increases the Gibbs free energy of the c-phase and decreases that of a-phase. Parts of the c-domains turn to a-domains, so as to reduce the remanent polarization of the PZT films.

To investigate the formation of grain boundary barriers, composite SnO 2 –Zn 2 SnO 4 varistor ceramics were prepared by traditional ceramic processing and, the electrical properties of grains and grain boundaries were evaluated by the measurement of complex impedances spectra. Calculated using the low frequency impedance data for each sample, a lower value about 0.09–0.32 eV and a higher value about 0.50–0.83 eV of activation energy E a was obtained in the temperature range of 50–110 and 140–200 °C, respectively. The simulated results of complex impedances spectra by “Zsimpwin” software indicate that the equivalent circuit for SnO 2 –Zn 2 SnO 4 composite ceramics is connected in series by one RC and two QR parallels. The relaxations in the dielectric dispersion spectra at low frequency of ∼1000 Hz suggest that one of the QR parallels is corresponding to oxygen vacancy. With increasing sintering temperature, the E a values related to oxygen vacancy decreased whereas, the values related to grain boundary barriers increase obviously. The results suggest that the oxygen vacancy is the key factor to the semi-conductance of SnO 2 grains and formation of grain boundary barriers.

Both undoped and Mn-doped BST films are fabricated on (1 1 1) Pt/Ti/SiO 2 /Si by metal organic deposition. X-ray diffraction and atomic force microscopy reveal the microstructure of the samples. The effect of Mn dopant on structural and electrical properties is studied. It is found that the dc leakage behavior and dielectric loss of the BST films are greatly improved due to the change of the valence state of Mn ions. Meanwhile, the tunability of Mn-doped BST films is suppressed, and the possible causes of tunability dependence are discussed.

The effect of nitrogen on the denuded zone (DZ) in Czochralski CZ silicon has been investigated. After the DZ formation, the CZ and the nitrogen-doped CZ (NCZ) silicon wafers were subjected to prolonged annealing. It is found that the DZ of the NCZ silicon only shrinks a little during the prolonged annealing, and no new oxygen precipitates are formed in the DZ, which is the same as the corresponding CZ wafer. Therefore, it is considered that no tiny oxygen precipitates existed in the DZ of the NCZ-Si by IG treatment, which can satisfy the requirements of microelectronics industry. Based on the facts, the effect mechanism of nitrogen on the DZ is discussed.

The effect of nitrogen doping on grown-in crystal originated particles (COPs) in Czochralski (CZ) silicon and COP annihilation during annealing in hydrogen at high temperature has been investigated. It is found that nitrogen doping leads to denser COPs in smaller sizes during CZ silicon crystal growth. Meanwhile, it is clarified that the grown-in COPs in the nitrogen-doped CZ (NCZ) silicon can be annihilated at a much lower temperature compared to those in the CZ silicon, furthermore, the denude zone (DZ) with lower COP density in NCZ silicon was much wider than that in CZ silicon. It is reasonably concluded that the nitrogen doping reduces the supersaturation of vacancies prior to the void formation and thus decreases the onset temperature of void formation, so the size of the void is smaller and the oxide films on the inner walls of the void are assumed to be thinner in NCZ silicon, compared with those in CZ silicon. Therefore, the voids in NCZ silicon can be annihilated more easily by hydrogen annealing.

The intrinsic gettering (IG) of germanium-doped Czochralski (GCZ) silicon with different concentrations of germanium has been investigated in this paper. The conventional Czochralski (CZ) and the GCZ silicon samples were annealed using a one-step high temperature process followed by a sequence of low–high temperature annealing cycles. It was found that the good defect-free denude zones in the near surface of the GCZ silicon could be achieved using simply a one-step high temperature annealing process. Furthermore, the density of bulk microdefects as IG sites was higher than that in the CZ silicon, as a result of germanium enhancing oxygen precipitation during three-step annealing. Meanwhile, the experimental results showed that germanium also enhanced the out-diffusion of oxygen. Furthermore, it is believed that germanium doping can increase the ability of IG in CZ silicon wafers.

In this paper, we investigate oxidation-induced stacking faults (OSFs) and related grown-in oxygen precipitates of nitrogen-doped Czochralski (NCZ) silicon. The samples were oxidized at 1150 °C or were annealed under different conditions. It was found that OSFs with different densities in the NCZ silicon distributed not only in the OSF-ring region, but also in the inner region of the ring. Furthermore, the OSF ring was extended by nitrogen doping. In addition, the investigation of oxygen precipitates indicates that nitrogen changes the size and density distribution of grown-in oxygen precipitates in the OSF-ring and void regions of the NCZ silicon during crystal growth, and therefore the OSF behaviour is changed. Based on the experimental facts, in particular we discuss the mechanism of nitrogen affecting the distribution of OSFs in different regions.

The effect of germanium (Ge) on void defects in lightly Ge-doped Czochralski (GCZ) silicon (Si) crystals has been investigated. Three GCZ Si crystals with different Ge concentrations (10 15 –10 18 cm −3 ) and one conventional Czochralski (CZ) Si crystal were grown under almost the same growth conditions. It is found that the density of flow pattern defects (FPDs) related to void defects in the as-grown GCZ Si decreases with the increase of Ge concentration. The voids in the GCZ Si could be eliminated more easily during annealing at the high temperatures of 1050–1200°C. It is concluded that Ge can suppress the formation of voids during Si crystal growth. Thus, GCZ Si can be expected to use widely in modern microelectronic industry.

Both experiment and theory have shown that the stress has a notable impact on the polarization of Nd-doped Bi 4 Ti 3 O 12 films. In this paper, thermodynamic theory is used to study the effect of stress on the dielectric constants of Bi 4 Ti 3 O 12 films at room temperature with a two-dimensional model. Results indicate that the change of the dielectric constant for a-phase induced by the lattice distortion is far greater than that for c-phase. Considering the domain reorientation, the external tensile stress may lead to an obvious decrease in the effective dielectric constant of Bi 4 Ti 3 O 12 films.

A 300 mm, p-type, 〈1 0 0〉-oriented nitrogen-doped Czochralski (NCZ) silicon crystal was grown in a Keyex MCZ 150 crystal puller equipped with cusp magnetic field. In order to dope nitrogen into the crystal, the primary protection gas of argon was mixed with high-purity nitrogen gas at a flow rate ratio of 10:1. Due to the long time growth of crystal, any perturbation due to the SiO and cristobalite particles at the crystal/melt interface would generate dislocation in the crystal. In order to avoid this ‘disaster’ during the crystal growth, a thermal shield in connection with a protection gas director was used, thereby generating a sweeping flow over the melt to drive the SiO and cristobalite particles out of the crystal/melt interface. The oxygen precipitation behavior of a near-seed-end wafer subjected to 800 °C/8 h+1000 °C/16 h was investigated. It was found that oxygen precipitation within the P-band was stronger than that in the region outside of the P-band, which is generally not the case for the conventional Czochralski (CZ) wafer with P-band. Based on this result, it is deduced that the grown-in oxygen precipitates existing in the P-band are relatively smaller in size but with higher density compared to those in the CZ crystal.